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AU783770B2 - Coating for drinking water pipelines - Google Patents
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AU783770B2 - Coating for drinking water pipelines - Google Patents

Coating for drinking water pipelines Download PDF

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AU783770B2
AU783770B2 AU81431/01A AU8143101A AU783770B2 AU 783770 B2 AU783770 B2 AU 783770B2 AU 81431/01 A AU81431/01 A AU 81431/01A AU 8143101 A AU8143101 A AU 8143101A AU 783770 B2 AU783770 B2 AU 783770B2
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Australia
Prior art keywords
methylenebis
oligomeric
polyamines
coating
poly
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AU81431/01A
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AU8143101A (en
Inventor
Ian Robinson
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3M Innovative Properties Co
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E Wood Ltd
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Assigned to 3M INNOVATIVE PROPERTIES COMPANY reassignment 3M INNOVATIVE PROPERTIES COMPANY Alteration of Name(s) in Register under S187 Assignors: E. WOOD LIMITED
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  • Polyurethanes Or Polyureas (AREA)

Description

AUSTRALIA
Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): E. WOOD LIMITED Invention Title: COATING FOR DRINKING WATER PIPELINES The following statement is a full description of this invention, including the best method of performing it known to me/us: Soo.
00 0 0 0:.00 Title: "Coating for drinking water pipelines" THIS INVENTION RELATES to two-part, rapid setting coating systems useful as internal linings for pipelines carrying drinking water.
The use of two-part coating systems, in particular those based on liquid epoxide resins and polyamine curing agents, to form protective linings for drinking water pipelines is well known. Such two-part systems have a demonstrable track record for both the "in-situ" refurbishment of existing water mains and for the protection of new pipelines. They provide thin, smooth linings with excellent carrying capacity and long term durability. However, these systems exhibit one main limitation for "in-situ" use in that due to their relatively slow hardening characteristics it is necessary to allow the coatings to harden minimally for 16 hours before returning the pipeline to service.
European Patent Application EP-A-0936235 discloses the use of aliphatic polyisocyanates blended with liquid epoxide resin or non-reactive resin, in combination with selected aromatic diamines, to provide rapid setting coating compositions useful as internal linings for pipelines, in particular as "in-situ" applied linings for refurbishment of drinking water pipelines. Such compositions, by virtue of their rapid setting characteristics, allow return to service in 2 hours or less with no adverse effects on water quality.
EP-A-0936235 teaches the use of a liquid epoxide resin or non-reactive resin in order to extend the gel time, reduce the heat of reaction and reduce the shrinkage of the pure polyurea systems obtained from the combination of aliphatic polyisocyanate(s) with aromatic polyamine(s).
It would be advantageous if the present invention provided a two-part coating system that can be applied to internal pipeline surfaces so as to form, at a high cure rate, an impervious lining suitable for contact with drinking water.
According to a first aspect, there is provided a method of forming a coating on the internal surface of a drinking water pipeline, the method comprising the steps of: providing a first part comprising one or more aliphatic polyisocyanates; providing a second part comprising one or more aromatic polyamines and one or more oligomeric polyamines blended together; mixing together the first part and the second part to form a mixture; and applying the mixture as a coating to said surface, and allowing the coating to cure by reaction of the polyamines with the polyisocyanate or polyisocyanates.
By virtue of its rapid setting characteristics and insensitivity to moisture, the system according to this aspect is particularly useful as an "in-situ" applied lining for refurbishment of existing drinking water pipelines.
S SThe first part of a two-part coating system may comprise one or more aliphatic Spolyisocyanates, optionally blended with one or more "amine reactive" resins and/or non-reactive resins.
25 The aliphatic polyisocyanate(s) can be any organic isocyanate compound containing at least two isocyanate functional groups, said isocyanate groups being aliphatic in nature.
Suitable polyisocyanates include hexamethylene- ,6-diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; isophorone diisocyanate; 4,4' -dicychohexylemethane diisocyanate. Alternatively, reaction products or prepolymers derived from the above may be utilised. For the purposes of the present invention, the preferred polyisocyanates are derivatives of hexamethylene-l,6-diisocyanate. The polyisocyanate compounds have a preferred isocyanate content of between 5 and 50%, with 20-25% being particularly preferred.
3 The "amine reactive" resin(s) can be any compound containing functional groups which are capable of reacting with primary or secondary amines. Useful materials include epoxy functional compounds and any compounds containing unsaturated carbon-carbon bonds capable of undergoing "Michael Addition" with polyamines, e.g. monomeric or oligomeric polyacrylates. For the purposes of the present invention, liquid epoxide resins or oligomeric polyacrylates are preferred.
Non-reactive resins, whilst not currently preferred in the present invention, may be employed provided that they have no resulting adverse effects on water quality.
The aromatic polyamine of the second part may comprise any organic compound containing at least two primary or secondary amine groups, wherein said amine groups are substituted directly to an aromatic moiety. Suitable aromatic polyamines include diethyl toluenediamine; dimethylthio toluenediamine; 4,4' -methylenebis (2-isopropyl-6-methylaniline); 4,4'-methylenebis (2,6-diisopropylaniline); 4,4' -methylenebis (2,6-dimethylaniline); 4,4' -methylenebis (2,6-diethylaniline); 4,4' -methylenebis (2-ethyl-6-methylaniline); 4,4' -methylenebis (3-chloro-2,6-diethylaniline). For the purposes of the present invention, diethyl S. 20 toluenediamine is particularly preferred.
The oligomeric polyamine can be any higher molecular weight organic compound containing at least two primary or secondary amine groups, said amine groups being either aliphatic, cycloaliphatic or aromatic in nature. Suitable compounds include poly 25 (oxypropylene) diamines, poly (oxypropylene) triamines, poly (oxytetramethylene)-di-p-aminobenzoates. For the purposes of the present invention, the preferred compounds are poly (oxypropylene) diamines and poly S: (oxytetramethylene) di-p-aminobenzoates. The preferred oligomeric polyamines have a molecular weight in the range 400-6000, with molecular weights of 500-3000 particularly preferred. Whilst not currently preferred in the present invention, a second part composed solely of oligomeric polyamines or non-aromatic polyamines may be employed provided that there are no resulting adverse effects on water quality.
The method may comprise applying the mixture through heated airless spray equipment.
The spray equipment may include a centrifugal spinning head or self-mixing spray gun assembly.
Various two-part systems embodying the invention are described below, by way of non-limiting example.
EXAMPLES
Table 1 below shows the results obtained when the liquid epoxide resin (Diglycidyl ether of Bisphenol A, "BADGE") in the preferred formulation(s) set out in European Patent Application EP-A-0936235 was replaced by alternative amine reactive resins, viz. monomeric or oligomeric polyacrylates.
:e ee a.* TABLE 1 Amine Addition Film Set Linear Film Integrity Reactive Level (Parts Time (Mins) Shrinkage in Presence of Resin per 100 of 1 mm Film Water polyiso- 3 0
C
cyanate) 0 2.5 0.150 Excellent BADGE 20 4 0.090 Excellent 5 0.040 Excellent Trimethylol- 0 2.5 0.150 Excellent propane 20 3.5 0.100 Excellent triacrylate 40 4.5 0.050 Excellent Penta- 0 2.5 0.100 Excellent erythritol 20 4 0.085 Excellent triacrylate 40 5 0.035 Excellent Dipenta- 0 2.5 0.150 Excellent erythritol 20 4 0.090 Excellent pentaacrylate 40 5 0.040 Excellent It can be seen from these results that other "amine reactive" resins e.g.
monomeric or oligomeric polyacrylates can usefully reduce the shrinkage of aliphatic polyisocyanate aromatic polyamine systems, whilst still retaining rapid setting capability at low temperatures under adverse (wet) conditions.
Table 2 below shows the results obtained when the basic aliphatic polyisocyanate-aromatic polyamine system was modified by blending oligomeric polyamines with the aromatic polyamine.
r r r TABLE 2 Aromatic Oligomeric Film Set Linear Film Integrity polyamnine! polyamine Time (Mins) Shrinkage in Presence of oligomeric 1 mm Film Water polyainine 3 0
C
ratio Poly(oxypropylene) 3.5 Mins 0.030 Excellent Poly(oxytetra- 50/50 methylene)- 4.5 Mins 0.027 Excellent Di-p -aminobenzoate 50/50 Blend of the 4 Mins 0.028 Excellent Poly(oxypropylene) 4 Mfins 0.028 Excellent diamine Poly(oxytetra- 40/60 methylene)- 5 Mins 0.025 Excellent Di-p-aminobenzoate 50/50 Blend (wiw) of the 4.5 Mins 0.026 Excellent above Poly(oxy- Gelled propylene) instantly N/A N/A diamine_______ Poly(oxytetra 0/100 methylene)- 8 Hours 0.005 Excellent Di-p-amino benzoate 50/50 Blend of the 5 Mins; 0.016 Excellent above 7 It can be seen from comparison of these results against those Illustrated in Table 1 that the incorporation of oligomeric diamines usefully reduces the shrinkage of the basic aliphatic polyisocyanate-aroinatic polyamine system, whilst again retaining the rapid film set and insensitivity towards moisture.
Table 3 below shows the results obtained from combining the work illustrated in Tables I and 2. In the examples shown, the oligomeric polyamine was a 50/50 blend of poly(oxypropylene) diamine and poly(oxytetramethylene)di-p-aminobenzoate.
TABLE 3 Aromatic Amine Addition Film Set Linear Polyamine! Reactive level Time Shrinkage Oligomeric Resin (Parts per 100 (Mins) 1 mm Polyamine of polyiso- Film 3 0
C
Ratio _______cyanate) BADGE 20 4.5 0.025 5 0.023 50/50 Dipenta- 20 4.5 0.024 erythritol 40 5 0.022 pentaacrylate BADGE 20 5 0.023 -5.5 0.022 40/60 Dipenta- 20 5 0.022 erythritol 40 5.5 0.020 pentaacrylate In all cases, the film integrity under wet conditions was excellent.
8 It can be seen from these results that inclusion of the "amine reactive" resin can yield further reductions in shrinkage without significantly impacting on the film set time at low temperature.
Table 4 below shows the results obtained when a number of compositions representative of some of the preferred forms of the invention were evaluated for suitability for contact with drinking water in accordance with the requirement of BS 6920:2000. In all cases the coating compositions were applied at a nominal film thickness of Imm and allowed to cure for 30 minutes at 3°C prior to commencement of testing. In examples illustrated, the oligomeric polyamine "blend" was a 50/50 blend of poly(oxypropylene) diamine and poly(oxytetramethylene)-di-p-aminobenzoate, with the "amine reactive" resin employed at an addition level of 25 parts per 100 of polyisocyanate TABLE 4 r r r r System Oligomeric Aromatic Amine BS6920:2000 Polyamine Polyamine/ Reactive Test Result Oligomeric Resin Polyamine Ratio (w/w) A 100/0 Dipenta- PASS erythritol pentaacrylate B Poly(oxy- 50/50 PASS propylene) diamine C Poly(oxytetra- 50/50 PASS methylene)- Di-p-aminobenzoate D Blend 50/50 PASS E Blend 50/50 BADGE PASS F Blend 50/50 Dipenta- PASS erythritol pentaacrylate These results show that the invention allows quite wide formulatory latitude in designing coating systems which will set rapidly under adverse conditions (for example when applied underground, in-situ to an existing drinking water pipeline) without having any deleterious effects on water quality.
Table 5 below illustrates some of the differences in physical and mechanical properties of the compositions detailed in Table 4. All the compositions were cured for 24 hours prior to testing. Flexural properties were determined in accordance with BS EN ISO 178:1997 and tensile properties in accordance with BS EN ISO 527:1996.
TABLE System Flexural Strength Tensile Strength Elongation (M Pa) (M Pa) Break A 55.2 28.4 2 B 43.0 29.5 C 52.0 33.0 D 44.8 28.0 E 43.5 27.2 F 44.0 27.7 These results illustrate that variations in composition, within the scope of the invention, allow the design of coating systems to meet specific design criteria whilst still satisfying the key requirements for in-situ application to drinking water pipelines.
In the present specification "comprises" means "includes or consists of" and "comprising" means "including or consisting of'.
The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.
For the purposes of this specification it is to be clearly understood that the word "comprising" means "including but not limited to", and that the word "comprises" has a corresponding meaning.
A reference herein to a prior art document, or other prior art information, is not an admission that the document or other information forms part of the common general knowledge in the art in Australia.
C C ooooo o

Claims (11)

1. A method of forming a coating on the internal surface of a drinking water pipeline, the method comprising the steps of: providing a first part comprising one or more aliphatic polyisocyanates; providing a second part comprising one or more aromatic polyamines and one or more oligomeric polyamines blended together; mixing together the first part and the second part to form a mixture; and applying the mixture as a coating to said surface, and allowing the coating to cure by reaction of the polyamines with the polyisocyanate or polyisocyanates.
2. A method according to Claim 1 wherein the or a said polyisocyanate is selected from the group comprising: hexamethylene-1,6-diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; isophorone diisocyanate; and 20 4,4' -dicychohexylemethane diisocyanate, or is derived from a member of said group.
3. A method according to Claim 1 or Claim 2 wherein the aromatic polyamine is selected from the group comprising: 25 diethyl toluenediamine; dimethylthio toluenediamine; 4,4' -methylenebis (2-isopropyl-6-methylaniline); 4,4' -methylenebis (2,6-diisopropylaniline); 4,4' -methylenebis (2,6-dimethylaniline); 4,4' -methylenebis (2,6-diethylaniline); 4,-methylenebis (2-ethyl-6-methylaniline); and 4,4' -methylenebis (3-chloro-2,6-diethylaniline). 12
4. A method according to any of Claims 1 to 3 wherein the oligomeric polyamine contains at least two primary or secondary amine groups, said amine groups being either aliphatic, cycloaliphatic or aromatic in nature.
5. A method according to any one of Claims 1 to 3 wherein the or a said oligomeric polyamine is selected from the group comprising: poly (oxypropylene) diamines; poly (oxypropylene) triamines; and poly (oxytetramethylene)-di-p-aminobenzoates.
6. A method according to any one of Claims 1 to 3 wherein the or a said oligomeric polyamines has a molecular weight in the range 400-6000.
7. A method according to Claim 6 wherein the or a said oligomeric polyamines has a molecular weight in the range of 500-3000.
8. A method according to any of Claims 1 to 7 wherein said first part includes one or more amine reactive resins blended with said polyisocyanate or polyisocyanates. 20
9. A method according to Claim 8 wherein said amine reactive resin is diglycidyl either ofbisphenol A or dipentaerythritol pentaacrylate.
A method according to any preceding claim wherein the mixture is applied through heated airless spray equipment.
11. A method according to Claim 10 wherein said spray equipment includes a centrifugal spinning head or self-mixing spray gun assembly. DATED this 8 th Day of September 2005 E. WOOD LIMITED By their Patent Attorneys GRIFFITH HACK
AU81431/01A 2001-10-18 2001-10-18 Coating for drinking water pipelines Ceased AU783770B2 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0431728A1 (en) * 1989-09-25 1991-06-12 Texaco Chemical Company Spray polyurea elastomers with improved abrasion resistance
EP0936235A1 (en) * 1998-02-11 1999-08-18 E. Wood Limited New coating for pipelines, tanks and structural steelwork

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0431728A1 (en) * 1989-09-25 1991-06-12 Texaco Chemical Company Spray polyurea elastomers with improved abrasion resistance
EP0936235A1 (en) * 1998-02-11 1999-08-18 E. Wood Limited New coating for pipelines, tanks and structural steelwork
US6074702A (en) * 1998-02-11 2000-06-13 E. Wood Limited Coating for pipelines, tanks and structural steelwork

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